Protocol Documentation

AMQP is a standard wire-level protocol and semantic framework for high performance enterprise messaging.

From the AMQP website:

AMQP is an Open Standard for Messaging Middleware.
By complying to the AMQP standard, middleware products
written for different platforms and in different
languages can send messages to one another. AMQP
addresses the problem of transporting value-bearing
messages across and between organisations in a timely
manner.
AMQP enables complete interoperability for messaging
middleware; both the networking protocol and the
semantics of broker services are defined in AMQP.